Background: Inflammatory cytokines and matrix metalloproteinases (MMPs) produced by resident and inflammatory cells in response to periodontopathogens play a major role in the tissue destruction observed in periodontitis, which is a disease that affects tooth-supporting structures. In the present study, we investigate the effects of licorice-derived licoricidin (LC) and licorisoflavan A (LIA) on the secretion of various cytokines and MMPs by human monocyte-derived macrophages stimulated with Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) lipopolysaccharide (LPS).
Methods: Macrophages were treated with non-toxic concentrations of LC or LIA before being stimulated with A. actinomycetemcomitans LPS. The secretion of cytokines and MMPs and the activation of nuclear factor-kappa B (NF-κB) p65 and activator protein (AP)-1 were assessed by enzyme-linked immunosorbent assays.
Results: LC and LIA inhibited the secretion of interleukin (IL)-6 and chemokine (C-C motif) ligand 5 in a concentration-dependent manner but did not affect the secretion of IL-8 by LPS-stimulated macrophages. LC and LIA also inhibited the secretion of MMP-7, -8, and -9 by macrophages. The suppression of cytokine and MMP secretion by LC and LIA was associated with the reduced activation of NF-κB p65 but not that of AP-1.
Conclusion: The present study suggests that LC and LIA have potential for the development of novel host-modulating strategies for the treatment of cytokine and/or MMP-mediated disorders such as periodontitis.